V8 Jaguars

[John S Farrington]

The comments above totally agree with my conclusions. The 6 cylinder Jag engines are adequately powerful and have great longevity built in (bulletproof past 200k miles). The V12 is a tour de force for engineering but demands high maintenance due to complexity and cramped space around the "large" engine compartment. Most of the problems of Jaguars are electrical in nature and most are due to improper or slipshod maintenance this side of the Atlantic. V8 conversions like Johns in Dallas are expensive and very dependent on the quality of the installation which varies widely. The average overhaul for a well used 6 cylinder Jag is about $4000. Compare this to a V8 conversion cost for a used V8 and there is no clear winner on the cost balance. If the V8 has to be overhauled it is the more expensive alternative. A Jaguar with the original power plant will always be easier to sell or trade. Most conversions go begging when on the selling block. Stay with the Jaguar power, enjoy and take good care of it!! Find a decent service outlet if you need it.

 

[John S Farrington]

You have received very good advice for the most part on V8 conversion of Jag sedans. I will offer what I think is a summary flavored with my personal opinion. The six cylinder Jag engines are robust with adequate power. Their reliability has been tainted by poor maintenance on this side of the Atlantic. The six cylinder XK or XJ40 engine are high quality powerful units with great longevity provided that they are maintained properly. Most problems with XJ Jaguar models are electrical, not mechanical. The electrical problems usually are derived from improper and even ignorant maintenance and repairs. XK units may be overhauled for about $4000. XJ40 units are somewhat more expensive due to the more complex valve arrangement. I submit that a conversion costs a lot more, particularly if the V8 is to be reconditioned before it is installed. Both reconditioned units will have great longevity but the original Jaguar engine will have much greater resale value. I have seen V8 conversions go begging for another owner when placed on sale. A quick look at resale ads in most sources of Jaguar used cars will confirm this. My advice is to stay with the Jaguar 6 unless you cannot find or live with available sources of electrical/mechanical maintenance.
On anather note, the 12 cylinder Jags are magnificant, smooth and powerful units that are engineering tour de force. The cost of overhaul or head work among other factors make V8 replacement practical. Since the market for used V12s is not very good due to relativily high availability, complexity and engine inaccessibility that produce high maintenance costs. The situation is quite different. I still prefer and recommend staying with the Jaguar engine if you can bear the tariff. I would also recommend getting a Corvette if you want a Chevy V8. I hope that this discussion thouroughly confuses the Johns V8 conversion issue. Pureism and authenticity aside, long live the 4.2 liter XK engine!!

 

[spit_head]

Why build up a stock 280 + Hp Jag. and want to compare it to a 180 to 210 Hp american anchor??? /ubbthreads/images/graemlins/hammer.gif

 

[J. Christian]

I had been considering a transplant for my 1979 XJ6 (actually, that was the reason I bought it in the first place), but on further reflection, have decided to keep the Jag powerplant for exactly the reasons pointed out above. If it were a 12 cylinder in need of an overhaul, I might reconsider, but I have over 100,000 miles on mine, and after a tune up, it is plenty strong. The only change that I might make is to switch from the troublesome EFI to carbs.
I would also like to point out that this thread has been active for almost three years!! There are obviously people that feel quite strongly about both sides!